JPH0643965B2 - Sensor element for measuring substance concentration - Google Patents

Abstract

Because of the size of the devices for the excitation or measurement of light, conventional sensor elements for optical determination of the concentration of substances in gaseous and liquid probes, which have an indicator layer with at least one indicator substance are only conditionally suitable for microanalysis instruments, or cannot be produced simply by mass production. To circumvent these disadvantages, it is proposed that at least one photosensitive element (3) and its electrical contact are integrated in a planar arrangement on the carrier layer (1), and that the indicator substance (7, 7') of the indicator layer (6), which is excited by the exciting radiation (11) is in optical contact with the photosensitive elements (3). <IMAGE>

Description

The present invention relates to a sensor for measuring the concentration of a substance in a gaseous or fluid sample, which comprises a carrier layer and an indicator layer having at least one indicator substance. A device in which at least one optical property of the indicator substance changes in interaction with the substance to be measured in response to the concentration of the substance.

[Conventional technology]

Optical sensors for measuring a substance concentration with an indicator substance, in particular such as to change the fluorescent indicator properties of the indicator substance through interaction with the substance to be measured, are well known techniques. From German Patent No. 2508637, for example, a sensor element of the type mentioned at the outset is known, whereby a thin layer of indicator solution is applied to a suitable carrier material, the indicator solution being dependent on the substance to be measured. Covered by a permeable membrane. On the carrier side of this structure, an irradiation device and an optical measuring device each having an optical element connected in series are arranged in the path of the excitation beam and the fluorescence beam.

In the arrangement known from East German Patent 106086, the fluorescent indicator is present in a layer which extends over the measuring chamber and the reference measuring chamber, this indicator layer being however in the region of the reference measuring chamber relative to the medium to be measured. Covered. The difference in fluorescence intensity between the measurement chamber and the reference measurement chamber is directly linked to the concentration of the substance to be measured. Fluorescence from the two measurement chambers is sent to each photoelectric converter using a fiber optic cable.

The sensor described above is thus generally composed of a reaction chamber which can be formed in the form of a thin layer, in which the indicator substance is present in a predetermined geometrical arrangement. From the side not facing the sample, light of a predetermined wavelength is sent to the indicator layer through a luminescence source and a suitable optical device such as an optical cable or an optical fiber. The fluorescence scattered by the indicator layer, i.e. emitted in all directions, is sent to the photodetector from about the same side of the reaction chamber or indicator layer again using suitable optical means and a corresponding filter device. The side of the reaction chamber not facing the optical device is in contact with the gaseous or liquid sample, the substance to be measured then generally being able to reach the reaction chamber by diffusion, and the indicator molecule of the indicator substance. And the indicator changes its optical properties, in particular its absorbance, in response to the substance concentration. The degree and tendency of this change have a functional relationship with the element to be measured.

[Problems to be solved by the invention]

The size of such an arrangement is determined, on the one hand, by the size of the sensor itself and, on the other hand, by the shape and size of the optical device, in particular the device required to extract the fluorescence or reflected beam. In the case of this type of sensor, for example in microanalyzer applications, it can be significantly miniaturized and can be manufactured in a mass-production technically simple manner, using as many conventional reaction chambers and / or indicator layers as possible. The challenge has arisen. However, the conventional sensor element has a problem that this problem cannot be solved.

[Means for solving problems]

This problem is due to the fact that in the sensor element according to the invention, at least one photo-sensitive element and its electrical connection means are integrated in the carrier layer with a flat formation structure and the indicator substance of the indicator layer excited by the excitation beam is It is solved by optically connecting with the sensitive element.

[Action, effect]

In this case, all layers of the sensor are manufactured by conventional microelectronics, i.e. photolithographic or planar techniques, such as evaporation, sputtering, spinning, etching, ion implantation, etc., and the sensor elements are provided as thin layers. Due to the integration of the photo-sensitive element and its electrical connection means on the substrate, the required ultra-miniaturization of the whole sensor structure is achieved, including the device for capturing the fluorescent or reflected beam. With this, the acquisition of the beam to be measured is expediently carried out in the sensor element itself, which eliminates all the optical devices heretofore required for optical measurements other than the sensor element. The measurement signal is sent directly to the display or evaluation electronics via the appropriate electrical signal line.

The electrical connection between the optoelectronic components in the sensor element is not limiting in the sense of the invention. This is because the corresponding connecting lines are in any case formed by the well-known microelectronics technology.

Advantageously, the sensor element according to the invention may use well-known indicator layers which serve various special purposes. The formation of various indicator layers for sensors of that kind, in particular on the basis of changes in the absorption or fluorescence of the indicator molecules, for the measurement of oxygen, CO _{2 and} PH values or of the ionic concentration of such species, is described in European Application No. 0109958, 010995.
No. 9, and 0105870, which are used to their advantage in combination with the present invention.

It is of course also possible to use the sensor layer according to US Pat. No. 4,568,518, in which case the carrier membrane, for example made of cellulose, is permeated by a separate network made of a material containing indicator material and reactive groups.

To create a favorable excited state for the indicator substance,
Alternatively, in order to allow good separation of the excitation beam from the beam to be measured, the geometry in one embodiment of the invention comprises at least one region that is transparent to the excitation beam and comprises a photo-sensitive element. It is required that there is a coupling layer between the containing substrate and the indicator layer that is transparent to the excitation beam and the beam to be measured. This optically transparent coupling layer, eg SiO
_{The 2} is deposited by a suitable microelectronic technique such as sputtering. The thickness of this layer depends on the geometry of the topographical arrangement of the individual photo-sensitive elements. The substrate provided with the photo-sensitive element can also be composed of the same material as the coupling layer, in which case the photo-sensitive element and its electrical connection are directly attached to the carrier layer and subsequently poured into the coupling layer. . Through this individual element or its optical coupling layer there is arranged an indicator layer with a fluorescent indicator which consists essentially of a polymer over the area of the entire structure.

In order to achieve a better optical and geometrical separation of the excitation beam from the beam to be measured, in another embodiment according to the invention, a coupling layer with a refractive index n ₂ is provided on both sides with a refractive index n. ₁ to form a flat light guide for the beam to be measured, the refractive index n ₂ being greater than the refractive index n ₁ and the one facing the sample. The boundary layer comprises at least one void, the void being provided with an indicator layer, said void being located above a region transparent to the excitation beam when viewed in the direction of the excitation beam; And the total internal reflection of the beam to be measured is eliminated in the region of the photo-sensitive element. The glass layer required for the light guide is deposited by reactively assisted sputtering. The central layer or coupling layer for guiding light should be thicker than 1 μm, which corresponds to several times the beam wavelength to be measured,
This layer can guide light well. The boundary layers provided on both sides should be 1-2 μm thick in order to have sufficient dimensions for the falling field of the guided wavelength. The divergence of the excitation beam this configuration, edge beams steep angle at the interface n _{2 /} n _1, so go lost, no much sense.

In a particularly advantageous embodiment according to the invention, only one region is provided which is transparent to the excitation beam,
A sensor of this type in which a photo-sensitive element such as a photodiode has a concentric and circular structure with respect to the region,
This can be achieved, for example, by etching out a ring-shaped diode structure from a wafer on which all the layers of the photodiode (as a photo-sensitive element) have already been placed. The resulting central circular opening is filled with glass having a refractive index n ₁ by sputtering. Further, a glass or resin layer having a refractive index n ₂ is again formed by sputtering or spinning. N ₂ should be greater than n ₁ in order to cause the total reflection in the layer having a wherein a refractive index n _2. From the latter layer one central disc is removed by etching to create space for the sensor layer. The starting substrate is then drilled down to the glass layer, creating an entrance for the excitation beam. The central cavity for the sensor layer is filled with a dye-containing silicon layer (refractive index n ₂ ) for the production of gas sensors, for example. What is then important is that the silicon layer has an index of refraction much like that of the underlying layer in order to use the entire sensor volume as completely as possible.

In a more particular embodiment according to the invention, the excitation beam impinges on the indicator layer preferably at an angle α of between 40 ° and 60 ° and is intra-substrate so as to excite the indicator layer located above the photo-sensitive element. A transparent region is obliquely arranged in the. With this proposed excitation geometry,
Particularly good excitation of the region of the indicator layer located above the photo-sensitive element occurs, which improves the gain of the sensor utilization signal.

Due to the particularly advantageous delivery of the excitation beam, according to the invention, the end of the optical cable, in particular of the single fiber, is terminated in a region transparent to the excitation beam, and A filter layer, in particular an optical interference filter, is provided in the region which is transparent. With this, the wavelengths suitable for excitation of the indicator substance directly in the sensor are filtered from the excitation beam. The electrical cable carrying the measurement signal is preferably extended together with the optical cable, in which case a defined plug (for example a BNC plug or an optical transmission plug) is used for the signal or optical transmission.

According to a further variant with the advantages of the invention, the photo-sensitive elements provided in the micro-areas and the light-emitting sources arranged in the adjacent micro-areas have a flat structure on the carrier layer together with their electrical input / output lines. And the indicator substance of the indicator layer is optically connected to the light emitting source and the photo-sensitive element.

The additional integration of the light emitting sources further allows the overall size of the sensor structure to be reduced. As an advantage, this sensor element is provided with only a large number of electrical contacts, which eliminates all optical devices other than the sensor element.
In this case, a large number of light-emitting or fluorescent semiconductor regions are placed in adjacent micro-areas in a given topographical arrangement on a suitable carrier layer, and the photo-sensitive semiconductor areas are exposed to the photo-sensitive semiconductor areas with a narrow spatial adjacency. It is interposed in the form of a diode or phototransistor. Such sources include light emitting diode structures or thin film structures with electroluminescence (eg H. Anthosson et al., "Thin Film Electroluminescent Properties by SIMS and Other Analytical Techniques"; Analytical Chemistry, 1985, 322). ,
P175-180).
Semiconductor structures of this kind are deposited or formed by standard microelectronic techniques on a suitable substrate with dimensions of a few microns. The light emitting areas or sources are electrically connected so that they are both excited by applying a constant voltage or by applying a constant amount of current to emit the desired light beam. In semiconductor engineering, a group of materials is known in which, for example, light emitting diodes and electroluminescent layers are to be produced in order to emit a desired wavelength of interest upon electrical excitation. Furthermore, the advantage of this sensor lies in its manufacturability, which is technically simple in mass production.

When determining the electrolyte concentration in an aqueous solution, according to the previous proposal, the potential difference that occurs in the ion-selective layer of the ion-selective electrode, which is the value for the electrolyte concentration, is the potential difference. It is measured by attaching a potential-selective fluorescent indicator to the layer and measuring its fluorescence intensity. The sensor element according to the invention having an indicator layer according to the above proposal results in a sensor with very small dimensions.

In order to separate the emitted light and the returning light, according to the invention, an optically transparent cup is here provided between the light-emitting source and / or the photo-sensitive element on the one hand and the indicator layer on the other hand. It is required that the ring layer is placed.

However, it is entirely possible that the light-emitting source and the photo-sensitive element are not integrated on the same substrate, which, in a further embodiment according to the invention, is such that the semiconductor structure forming the light-emitting source and, if necessary, its electrical contacts are unique. Accumulated on the substrate of
The substrate is deposited in the micro areas of the carrier layer occupied by the luminescent source. For example, a Co-substrate is overlaid in advance on the basic substrate, ie on the carrier layer to which one type of optical semiconductor can be deposited, on which other structures are to be deposited. Of course, it is also possible to prepare the Co-substrate before attaching the photo-sensitive element.

There are basically no restrictions regarding the topographical arrangement of the light emitting components and the light sensitive components. However, it is required that each one or more light emitting sources be located next to one or more photo-sensitive elements.

In this case, it is also possible according to the invention to arrange the micro-areas in a checkerboard pattern on the carrier layer, wherein the micro-areas are alternately occupied by the light-emitting sources and the photo-sensitive elements.

In a further variant of the invention, the micro-areas are arranged in a honeycomb manner on the carrier layer, wherein at least two equally spaced photo-sensitive elements are provided, each with a different filter material for one emission source. It is also possible to arrange. Due to its geometric emission properties, each light source reaches only a certain part of the indicator substance in the indicator layer above it and excites it to fluoresce. From there, the fluorescence of the indicator substance is in principle emitted uniformly in all directions and reaches at least two equally spaced photo-sensitive elements. If this element is provided with a filter material having different transmission for different wavelengths, the intensity of the fluorescence spectrum in a number of wavelength regions can be determined simultaneously. In the hexagonal honeycomb structure described above, it is of course possible to surround one photo sensitive element with a plurality of light emitting elements to improve the signal gain of the sensor element.

Subsequently, in a further configuration according to the invention, the light emitting source, preferably the LED, is each surrounded by a photo-sensitive element of annular structure, preferably a photodiode or a phototransistor. Here a transmitter and a receiver; that is to say for example a photodiode and a phototransistor form an integrated unit.

The advantage of this arrangement is its high efficiency in the use of the reflection or fluorescence of the indicator molecule, since there is essentially a large overlap between the emission angle of the light source and the acceptance angle of the photoreceiver. Of course, it is also possible to use a square structure instead of the ring-shaped structure. Many such configurations can be connected in sequence and can be made sensitive by the appropriate mounting of an indicator layer or, in any case, optical filters for different analytical values.

The configurations described up to now have preferably been conceived for the use of fluorescent indicator substances, but can also be applied to absorption indicators. However, in a fluorescent indicator, the wavelength of excitation light and the wave of fluorescence are so-called Stokes shift (Stoks shift).
es-Schift), that is, they are clearly separated from each other by a wavelength difference, and have the advantage that they can be separated very sharply from each other by an optical filter attached to the light source side and the photo-sensitive element side, that is, both sides. ing. The above separation presents an additional measure to avoid unwanted noise in the measurement.

In order to solve the problem that the light emitting source and the photo-sensitive element cannot be attached to the same carrier layer under some circumstances and a suitable Co-substrate cannot be used, according to yet another variant according to the invention, The source and, on the other hand, the photo-sensitive elements in parallel planes to one another, the light-emitting source preferably forming an associated phosphor layer, which phosphor layer is further attached to a carrier layer and forms the photo-sensitive element. The semiconductor structure is integrated on a substrate overlying the fluorescent layer, said substrate comprising regions which allow optical connection between the fluorescent layer and the indicator layer. The photo-sensitive element is then deposited or formed on the basic substrate, on which the abovementioned layers, including the indicator layer, can be placed. A light source of suitable wavelength is placed under the substrate with the light transmissive region, and the light source sends the excitation light through an unconfined intermediate region between the photo sensitive elements. This light source can also be realized, for example, by a single electroluminescent layer.
In another possible variant, the sensor structure, which does not include the light-emitting element itself, is attached to the separately produced light-emitting means by hybrid techniques, such as gluing.

For substrates that are not optically transparent, the area required for the optical connection of the substrates is obtained by the introduction of perforations using hole etching or laser techniques.

The above principles of electro-optic component formation on different sides can be reversed, with a light-emitting source optionally provided on a light-transmissive substrate, with a light-sensitive element below the substrate. There is.

In a further variant according to the invention, an optical filter layer is placed between the substrate on which the photo-sensitive element is mounted and the fluorescent layer. In another embodiment of the present invention, the coupling layer is provided with a diffractive structure such as a periodic grating structure, and the diffractive structure deflects the excitation beam in the region of the indicator layer located above the photo sensitive element. There is. The diffractive structure in the coupling layer is used as a focusing optical element for the excitation beam, the slight structural height (holographic structure) of this grating structure providing the advantage. 0.3
In order to optimally utilize the holographic structure produced with a thickness of μm, as parallel light as possible with a small spectral bandwidth is used. The effect of this structure is only 5-10
Guaranteed with a divergence angle of ° and a spectral band of only 5-10 nm.

In order to better distinguish the excitation light from the fluorescence or to evaluate with respect to many different wavelengths, in another variant of the invention, the photosensing element and / or the light emitting source are additionally provided with an optical filter layer, preferably It can be covered by an optical interference filter. In the case of a suitable choice of fluorescent indicator, or in the case of scatter reflection measurements, it is not necessary for both photoelectric elements to each carry one filter layer.

Yet another embodiment according to the present invention takes advantage of the angular dependence of the spectral transmission of an interference filter, where there is an interference filter between the coupling layer and the indicator layer, which interference filter has a predetermined incidence angle. In contrast, the excitation beam and the fluorescent beam emitted from the indicator substance have different transmission coefficients. It is known that interference filters shift their transmission region towards shorter wavelengths unless the incoming beam is incident at a right angle to the filter surface. As a result, the spectral shift depending on the angle of transmission of the interference filter is used to distinguish between short-wavelength excitation light and long-wavelength fluorescence. In that case, the short-wavelength excitation light can pass through the filter layer only when the incident angle α is larger than a predetermined limit angle, for example, 30 °. Long-wavelength fluorescent light passes through the filter layer only when the incident angle β is smaller than a predetermined limit angle, for example, 25 °. The relative position of the photo sensitive element or the light emitting source with respect to the indicator layer is
Based on this optical fact, the signal gain is optimized for maximum. Prevents long-wavelength light emitted by an LED or its scattered light from reaching a photo-sensitive element, eg a phototransistor, when long-wavelength (spectral relative to fluorescence) light is emitted by a light emitting source, eg an LED. The appropriate angle condition is effective.

If it is intended to determine the concentration of many substances in a gaseous or liquid sample at the same time, in a further embodiment of the invention, the indicator layer is provided with micro-areas each provided with one photo-sensitive element, This microarea has a different indicator substance. Now, many different substances can be measured from the same sample at the same time using sensor elements with arbitrary topographical arrangements of light-emitting and photo-sensitive components. According to an advantageous embodiment of the invention, the indicator layer then consists of a porous glass, in which it is possible to immobilize the indicator substance.

For manufacturing PH-sensors, for example, microporous glass is used, which is sputtered. A dye is chemically immobilized on this, and if necessary, a protein-impermeable layer made of, for example, PVA is vapor-deposited.

In other configurations of the invention, the indicator layer may be comprised of, for example, spun or rolled silicon with the indicator substance contained therein.

In a particular embodiment according to the invention, the indicator molecule of the indicator substance is directly chemically connected to the optical coupling layer. If the material of which the optical coupling layer is composed is not suitable for direct immobilization, an overlying layer is deposited from another material, for example a suitable material, on which chemical immobilization of the indicator molecule takes place. It is possible to be.

It is also possible for the indicator substance to be deposited by microscreen printing or vapor deposition in order to deposit different indicator substances in the area of the indicator layer having a diameter of only 100 micrometers. A thin material layer is then distinguished by means of microscreen printing or other such method in defined areas set by a photographic mask.

It is also possible to provide a coating layer on the side of the indicator layer facing the sample. Briefly, this coating layer is composed of a thin polymer layer with injected dye to prevent excitation light and fluorescence from reaching the sample chamber, and undesired reflections of substances that are measured together as disturbing noise. Or fluorescence prevents excitation. The difference in the refractive index of the various sample materials becomes meaningless due to the adhesion of the coating layer. Furthermore, by means of a suitable coating layer, the macromolecular constituents of the sample which influence the measurement result can be kept away from the indicator layer. It is also possible to apply a coating layer having a selective action,
As a result, the substance to be measured can be preferentially scattered in the indicator layer. For the embodiment in which the coupling layer functions as a light guide, it is also possible to select a coating layer with a corresponding refractive index so that the coating layer takes over the task of the boundary layer on the side facing the sample. Is. Sensor elements that utilize absorption or scattered reflection of the indicator rather than fluorescence generally require the boundary layer of the indicator layer towards the sample to be provided with a reflective material and optionally an additional optical coating layer.

Yet another advantage of this type of flat microsensor is:
With the possibility of mass production by the already mentioned microelectronics technology, electronic circuits are integrated on the carrier layer and in any case further on the substrate connected to it,
The electronic circuit is capable of functioning for adjusting the brightness of the beam generated by the light emitting source and / or for amplifying the electrical signal of the photo-sensitive element.

Further integration is achieved according to the invention by providing a highly integrated electronic circuit on the carrier layer, which electronic circuit is responsible for the signal evaluation function. For example, by sputtering differently colored glass onto the light-sensitive elements of the individual micro-areas and by considering this color swatch, ie a filter with different transmission, in the microelectronic circuit, the color I Circuit I has circuit II associated with color II, so that multi-wavelength analysis can be realized directly in the sensor element. It is also possible to equip the part of the photo-sensitive element covering the light emitting source with the same filter material. In this case, the scattered or reflected excitation light is detected and used as a reference value for the light intensity.

EXAMPLE The sensor element according to the invention shown in FIG. 1 comprises a photo-sensitive element 3 on a suitable carrier layer 1 in a substrate 3'formed as a thin layer. Are integrated there in a flat forming structure parallel to the surface 4 of the carrier layer 1. The photo-sensitive element 3 is covered by an optically transparent coupling layer 5, for example of SiO ₂ , which is applied by suitable microelectronic techniques. It is also possible to attach the photo-sensitive elements 3 directly to the carrier layer 1, the coupling layer 5 of which is arranged on each photo-sensitive element 3.
It is also extended to the area between. On this coupling layer 5 is an indicator layer 6 having an indicator substance 7. The substrate 3 ′ is provided with a region 20 through which the excitation beam 11 can be transmitted, the excitation beam 11 being supplied therethrough via a transparent carrier layer 1—for example using a light guide not shown here. It This transmissive region 20 is provided with a filter layer 10 in order to obtain the desired wavelength for excitation of the indicator substance 7. After passing through this filter layer, the excitation beam 1
1 denotes a refraction structure 19 provided in the coupling layer 5, for example a holographic grating structure (diffraction grating), whereby the excitation beam 11 ′ deflected there is an indicator layer located above the photo-sensitive element 3. The focus is on area 6. The electrical connection of the photo-sensitive element 3 covered with the optical filter material 8 is detailed in the individual figures because it is integrated in the carrier layer 1 or in the substrate 3'using microelectronic techniques known per se. Not shown, only electrical contact pins or electrical contact cords 28 coming out of the sensor element through the carrier layer 1
It can be seen from FIG. 1 and from FIG. 4 which will be mentioned later, whichever the contact bin or contact cord is attached somewhere on the sensor element, it is within the scope of the invention. .

In order to avoid exiting the excitation beam 11 from the sensor element, ie causing undesired reflections or fluorescence in the sample in contact, the indicator layer is optically directed to the side 18 facing the sample. The sensor layer 6, which includes the coating layer 9,
That is, although it is the indicator layer, only the fluorescent beam 12 or the reflected beam from this point onward is detected. It is also possible to prepare different indicator substances 7, 7'for the respective regions of the sensor layer 6 arranged on the respective photo-sensitive elements 3.

Hereinafter, the same elements are given the same reference numerals in all embodiments.

In the variant embodiment shown in FIG. 2, a different concept realizes favorable excited and detected states. The excitation beam 11 coming through the transparent carrier layer 1 causes the substrate 3 '
It is directly guided to the region of the indicator layer 6 located above the photo-sensitive element 3 through the transmission region 20 'arranged obliquely. The angle between the excitation beam 11 and the indicator layer 6 is
Topographical arrangement of photo-sensitive elements and transmissive areas and individual layers,
Especially, depending on the thickness of the coupling layer 5, it is about 45 ° in the embodiment shown in FIG. An optical filter layer 10 ′ is provided between the carrier layer 1 and the substrate 3 ′, and the indicator substance 7
It is put in order to extract a convenient wavelength for excitation of. The beveled holes or transmissive regions 20 'in the substrate 3'are made by incorporating drilling using a suitable technique, such as laser technology.

FIG. 3 shows a sensor element in which a substrate 3 ′, which is embodied as a diode layer, is deposited on a transparent carrier layer 1. The diode layer is etched to create a transmission region 20 for the excitation beam 11, which excitation beam reaches further into the indicator layer 6 with the indicator substance 7 located above the transmission region. The coupling layer 5 located above the diode layer is bounded by boundary layers 21, 22 having a refractive index n ₂ and having a refractive index n ₁ provided on both sides, the coupling layer 5 being a boundary. Beam 12 to be measured with layers 21, 22
Is equipped with a flat light guide. The boundary layer 21 on the side facing the sample has an empty space 23 formed by etching, into which the sensor layer 6 is inserted. The coating layer 22 provided on the side opposite to the sample is the photo-sensitive element 3
It is replaced by a filter layer in the region of the (photodiode), which has a refractive index n _{3 at} which the total reflection of the excitation beam is eliminated (n ₃ is approximately n _2).
The excitation beam 11 incident perpendicularly on the boundary layer 22 passes through the coupling layer 5 and reaches the sensor layer 6 where it excites the indicator substance 7. The fluorescent beam 12 radiated in all directions is partially reflected by the boundary layers 21 and 22, and enters the photo-sensitive element 3 in the region of the filter 8 where the total reflection disappears. It is of course also possible to cover this sensor with a coating layer 9 on the sample.

The embodiment shown in FIG. 4 is a modification of the embodiment according to FIG. The starting material for this sensor is a wafer with a layer of photodiodes here designated 3 '(carrier layer 1 with substrate 3'). From this, in the first step, the ring-shaped photo-sensitive element 3 is formed by etching, and the central circular surface is uniformly filled with glass having a refractive index n ₁ , for example, by sputtering, whereby the excitation beam 11 is transmitted. A possible area 20 is formed. In the next step, the layer that realizes the coupling layer 5 is, for example, a sputtered colored glass filter or a spun resin filter, both of which have a refractive index of n _2.
It is made from those that have. In this case, the coupling layer 5 acts on the one hand as a light guide for the beam 12 to be measured and on the other hand as a selective filter layer 8 which separates the fluorescence beam from the reflected or scattered excitation beam. . An opening 26 located above the transmission region 20 is opened from the filter layer 8 by etching, and the opening 26 is filled with glass that transmits the excitation beam 11. Subsequently, the boundary layer 21 facing the sample and having the refractive index n ₁ is sputtered or spun, and the indicator layer 6 is put in the void 23 arranged concentrically with the opening 26. As the indicator layer 6, a porous glass layer on which an indicator substance 7 is immobilized or a silicon layer containing an indicator rolled in a disk-shaped cavity 23 is used. It is effective if the indicator layer 6 has a refractive index very similar to the coupling layer.

Finally, as a final step, a center hole 27 is created in the carrier layer 1, which reaches the boundary layer 22 filling the transparent region 20 and accommodates the end 24 of the optical cable 25. In that case, it is preferable to use a single-fiber optical cable. The contact cords 28 emerge here parallel to the optical cable 25 and are suitably fixed to form an optical-electrical fiber bundle. It can be considered that the sensor element according to the present invention shown in FIG. 5 is divided into, for example, a grid-shaped fine area a, b, but in such a suitable carrier layer 1 alternating. In the fine area a, the light-emitting source 2 and in the fine area b are provided the photo-sensitive elements 3, which are integrated in parallel with the surface 4 of the carrier layer 1 in a flat formation structure. The micro-areas a, b described on the basis of this embodiment
The topographical arrangement of is shown in FIG. 6 and the side lengths of the individual microzones are of the order of a few micrometers. The optoelectronic elements 2, 3 are covered by an optically transmissive coupling layer 5, for example made of SiO ₂ . In order to obtain the desired wavelength for the excitation of the indicator substance 7, the emission source 2, which is realized by a light emitting diode or an electroluminescent layer, is covered with an optical filter material 8 ', in which case the desired wavelength is selected from the fluorescence spectrum. For this purpose, a photo sensitive element 3, for example a phototransistor, is used as
It is also possible to cover with. The power supply path to the light-emitting source 2 or the signal transmission path from the photo-sensitive element is not shown here.

In the embodiment shown in FIG. 7, the excitation beam 11 having a short wavelength and a spectral deviation depending on the transmission angle of the interference filter 10 ″ disposed between the coupling layer 5 and the indicator layer 6 and the long wavelength are shown. It is shown that it can be used to discriminate between the wavelengths of the fluorescent beam 12. The light-emitting source 2 and the photo-sensitive element 3 are arranged on the same plane as in FIG.
The geometrical arrangement of the photoelectric elements 2, 3 with respect to each other, or also with respect to the interference filter 10 ″ and the indicator layer 6 located above it, has the following relationship: The short-wavelength excitation beam 11 The interference angle can be passed through the interference filter only when the incident angle α measured with respect to the ray is above a predetermined limit angle, eg 30 °. The long wavelength fluorescent beam 12 has an incident angle β of a predetermined limit angle, eg 25. It is possible to pass through the interference filter only when the angle is less than or equal to 0. The formation of the interference filter having this advantage is of course effective even when the light emitting source and the photo-sensitive element are not arranged on the same plane.

If the light-emitting source 2 and the photo-sensitive element cannot be integrated on the same carrier layer 1, as shown in FIG. 8, first the photo-electric component, on the carrier layer 1, in the micro-area b provided for it, For example, a type of the photo-sensitive element 3 is attached, and a light emitting source is integrated in the fine area a here. However, another substrate 13 (Co
-Substrate) can be attached. It is of course also possible to provide a Co-substrate for the photo-sensitive element 3 or to use a separate substrate for each type of photo-electric element 2, 3.

In the modified embodiment shown in FIG. 9, the light emitting source 2 and the photo sensitive element 3 are not arranged in the same plane. Fine area a
The light-emitting source 2 integrated in the carrier layer 1 therein has the associated phosphor layer 14 as shown in the previously described embodiments.
Can be formed, in which case the micro-areas a, b at least partially overlap. This fluorescent layer 14
Are covered by a substrate 15 with a filter layer 17 if necessary, on which the photo-sensitive elements 3 are integrated in the microscopic areas b. On top of that a coupling layer 5 and an indicator layer 6 are placed and, if necessary, covered by a coating layer 9. The substrate 15 on which the photo-sensitive element 3 is mounted is excited by the excitation light 1
1 is at least transparent, or at least has a region 16 which has been made transparent by perforation by etching holes or lasers. As already shown in FIG. 5, it is of course possible to cover the photo-sensitive element and the light emitting source with different filter materials, or to cover the individual photo-sensitive elements 3 with different filter materials. The fluorescent beam 12 can be valuated based on many different wavelengths. Photosensitive element 3
The individual micro-areas b of the sensor layer 6 in which are arranged can, of course, also be provided with different indicator substances 7, 7 ', which makes it possible to use many of the substances contained in the sample with the sensor indicator drug element. Concentration can be calculated simultaneously.

In the tenth configuration, the light emitting source 2 and the photo-sensitive element 3 form an integrated unit and have an annular structure. At this time, for example, the photodiode in the annular micro area a can be surrounded by the phototransistor in the annular micro area b. Multiple such integrated units can be integrated into one sensor element.

Finally, FIG. 11 shows a further topographical arrangement of the microzones, which here has a hexagonal honeycomb structure. At this time, for example, the light emitting source 2 is surrounded by a large number of photo sensitive elements 3 at equal intervals. This convenient arrangement allows various filter materials to be tested in the micro-area b,
By attaching to b ', multiple wavelength analyzes can be performed in a simple manner.

[Brief description of drawings]

The drawings show an embodiment of the sensor element according to the present invention, FIG. 1 is a sectional view of a part of the sensor element, and FIG. 2 is a sectional view showing a part of a modified example of the sensor element according to FIG. 4 is a sectional view showing a part of another embodiment of the sensor element, FIG. 5 is a sectional view showing still another embodiment of the sensor element, and is a sectional view taken along line VV of FIG. 6, and FIG. Sectional view taken along the line VI-VI in the figure,
FIGS. 7 to 9 are sectional views of another embodiment similar to FIG. 5, and FIGS. 10 and 11 are schematic views of sensor elements having different topographical arrangements of photoelectric elements. Is. 1 ... Carrier layer, 3 ... Photosensitive element 6 ... Indicator layer, 7, 7 '... Indicator substance 11 ... Excitation beam

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Otto S. Wolff Austria 8046 Graz im Hoffeld 32 (72) Inventor Helmut Liszt Austria 8010 Graz Borgengasse 36 (72) Inventor Alfred Reitna Austria 8010 Graz Theodor-Kerna Strasse 151 (56) References JP-A-60-40938 (JP, A)

Claims (25)

[Claims] 1. A sensor element for measuring the concentration of a substance in a gaseous or fluid sample, comprising a carrier layer and an indicator layer having at least one indicator substance, the optical element comprising at least one optical substance of the indicator substance. In the carrier layer (1), at least one photo-sensitive element (3) and its electrical connection means are formed flat, the properties of which change in response to the concentration of the substance in interaction with the substance to be measured. Indicator substance (7, 7 ') of said indicator layer (6) integrated with the structure and excited by an excitation beam (11)
A sensor element for measuring a substance concentration, which is optically connected to the photo-sensitive element (3). 2. A substrate (3 ') comprising at least one region (20) transparent to the excitation beam (11) and containing a photo-sensitive element (3) and an indicator layer (6). Excitation beam (11) and beam to be measured (1
Sensor element according to claim 1, characterized in that there is a coupling layer (5) which is transparent to 2). 3. Coupling layer (5) having a refractive index n _2.
There boundary layer (21 having a refractive index n ₁ which is provided on both sides,
22) to form a flat light guide for the beam (12) to be measured, the refractive index n ₂ being greater than the refractive index n ₁ and the one facing the sample. The boundary layer (21) comprises at least one void (23), which void is provided with an indicator layer (6) and said void (23) is seen in the direction of the excitation beam 1
1) Located above the region (20) transparent to the region (1) and characterized in that total reflection of the beam (12) to be measured does not occur in the region of the photo-sensitive element (3). The sensor element according to the second section. 4. A single region which is transparent to the excitation beam is provided, the photo-sensitive element (3) such as a photodiode having a concentric and circular structure with respect to said region. The sensor element according to any one of claims 1 to 3, wherein: 5. Excitation beam (11) preferably at 40 °-
A region transparent to the substrate (3 ') so as to enter the indicator layer (6) at an angle α of 60 ° and excite the indicator layer (6) located above the photo-sensitive element (3). The sensor element according to claim 2, wherein (20 ') is obliquely arranged. 6. The end (24) of an optical cable (25) such as a single fiber is terminated in a region (20) transparent to the excitation beam (11). 5. The sensor element according to any one of the first to fourth ranges. 7. A filter layer (10, 10 '), such as an optical interference filter, is provided in the region (20, 20') transparent to the excitation beam (11). 7. The sensor element according to any one of items 1 to 6 in the range. 8. A photo-sensitive element (3) provided in a fine area (b, b ') and a light emitting source (2) arranged in an adjacent fine area (a) are flat together with their electric input / output lines. Of the indicator structure (7, 7 ') of the indicator layer (6), which is integrated on the carrier layer (1) with a different formation structure and is optically connected to the light emitting source (2) and the photo-sensitive element (3). The sensor element according to claim 1, wherein: 9. An optically transparent coupling layer (5) between the light-emitting source (2) and / or the photo-sensitive element (3) on one hand and the indicator layer (6) on the other hand. The sensor element according to claim 8, wherein 10. The semiconductor structure forming the light-emitting source (2) and, if necessary, its electrical contacts are integrated into a unique substrate (13), which substrate (13) is occupied by the light-emitting source (2). 10. Sensor element according to claim 8 or 9, characterized in that it is deposited in the fine areas (a) of the carrier layer (1). 11. Microareas (a, b) are arranged on the carrier layer (1) in a grid pattern, wherein the microareas (a, b) are provided.
10. The sensor element according to any one of claims 8 to 9, characterized in that the light sources (2) and the photo-sensitive elements (3) are alternately occupied. 12. Microregions (a, b, b ') are arranged in a honeycomb pattern on the carrier layer (1), with at least two equidistant intervals for each light-emitting source (2). Sensor element according to any of claims 8 to 10, characterized in that a photo-sensitive element (3) with a different filter material is arranged. 13. A light-emitting source (2) such as an LED is surrounded by a photo-sensitive element (3) having an annular structure such as a photodiode or a phototransistor, respectively. The sensor element according to any one of item 10. 14. A light-emitting source (2) on the one hand and a photo-sensitive element (3) on the other hand are provided in mutually parallel planes, the light-emitting source (2) preferably forming the associated phosphor layer (14). Furthermore, this fluorescent layer (14) is attached to the carrier layer (1) and the semiconductor structure forming the photo-sensitive element (3) is integrated on a substrate (15) covering the fluorescent layer (14), and 10. The substrate (15) according to claim 8 or 9, characterized in that it comprises a region (16) enabling an optical connection of the fluorescent layer (14) and the indicator layer (6). The described sensor element. 15. A substrate (1) on which a photo-sensitive element (3) is mounted.
5) and the fluorescent layer (14) between the optical filter layer (17)
The sensor element according to claim 14, wherein there is 16. The coupling layer (5) has a diffractive structure (19) such as a periodic grating structure.
9. The method according to any one of claims 2 to 9, characterized in that 9) deflects the excitation beam (11) in the region of the indicator layer (6) located above the photo-sensitive element (3). The sensor element according to 1. 17. A photo sensitive element (3) or a light emitting source (2).
The sensor element according to any one of claims 1 to 16, characterized in that both or both are additionally covered with an optical filter layer (8, 8 ') such as an optical interference filter. . 18. A coupling layer (5) and an indicator layer (6)
An interference filter (10 ″) is present between the excitation beam (11) and the indicator substance (7, 7 ′) for a given incident angle (α, β). Claims 1 to 1, characterized in that they have different transmission coefficients for the emitted fluorescent beam (12).
6. The sensor element according to any one of 6. 19. The indicator layer (6) is provided with micro-areas (b, b ') each provided with one photo-sensitive element (3), said micro-areas being different indicator substances (7, 7'). ) Is included, The sensor element in any one of Claim 1- Claim 18 characterized by the above-mentioned. 20. The indicator layer (6) is made of porous glass, and the indicator substance (7, 7 ') is immobilized in the glass.
Item 9. The sensor element according to any one of items 9. 21. The indicator layer (6) consists of spun or rolled silicon, in which the indicator substance (7,
7 ') are provided, The sensor element in any one of Claims 1-19 characterized by the above-mentioned. 22. The indicator molecule of the indicator substance (7, 7 ') is directly chemically connected to the optical coupling layer (5), according to claims 2 to 19. The sensor element according to any one of claims. 23. Sensor element according to any one of claims 1 to 19, characterized in that the indicator substance (7, 7 ') is applied by microscreen printing or vapor deposition. 24. An electronic circuit is integrated on a carrier layer (1) and further on a substrate (13, 15) connected thereto, the electronic circuit being of a brightness of a beam produced by a light emitting source (2). 24. Sensor element according to any one of claims 1 to 23, characterized in that it functions for regulation or for amplification of the electrical signal of the photo-sensitive element (3) or both. 25. Sensor according to claim 24, characterized in that a highly integrated electronic circuit is provided on the carrier layer (1), which electronic circuit also has the function of signal evaluation. element.